Men who have sex with men (MSM) constitute a substantial proportion of HIV-positive populations around the world, and in most parts of the world are at markedly increased risk of anal HPV infection and anal disease (neoplasia). In many African countries homosexuality is criminalized, and even where MSM activity is not illegal (as in Rwanda) it is not well accepted in society. In these settings MSM generally do not come forward for medical care and many have not been screened for HIV. In developed countries, HIV-related malignancies constitute a growing source of HIV-related deaths, as Individuals live longer on ART antiretroviral therapy. In particular, the incidence of HPV-related anal cancer is growing among HIV-positive MSM. Among the four most common non-AIDS-defining malignancies, the largest increase has been in anal cancer. Understanding the prevalence and incidence of anogenital HPV infection and precancerous lesions and their associated risk factors in at-risk populations is particularly important since, unlike most other cancers, HPV-related cancers may be preventable. Rwanda is one of the few African countries that reaches out to MSM with HIV services, as part of their HIV control efforts. We therefore propose a study of 350 MSM in Rwanda enrolled over a year and followed every six months for two years to measure the prevalence and incidence of HPV-infection, HIV-infection and anal neoplasia.